| 摘要 |
1296786 Laser gyroscope HONEYWELL Inc 11 May 1970 [14 May 1969] 22618/70 Heading G1A [Also in Divisions H1 and G4] In a laser gyroscope two beams of monochromatic radiation are directed around a closed path defined by mirrors 2, 3 and 4 in opposite directions. The light beams are detected via mirrors 6 and 7 by photo-detector 8. If the system is rotated a frequency difference is produced between the two beams which may be detected in the form of a shifting fringe system. In order to prevent the two frequencies locking together in the laser, the optical system as a whole is oscillated so that the frequency difference between the two beams is always sufficient to prevent lock-in. The detector circuit 13 is designed so that the output appears on line 14 or line 15 according to the direction of rotation of the system. The pulse train output on lines 14 and 15 are fed via gates 29 and 30, which are NAND gates to a reversible counter 17. In this way the count recorded on counter 17 is the difference count between lines 14 and 15 and represents the next rotation in any one direction. The pulse trains are counted by counter 17 for a fixed number of oscillation periods of the rotating system, so that the next reading on counter 17 corresponds to true rotation and not the imposed oscillatory rotation. This gating is achieved by means of control circuit 16 which controls the switching of gates 29 and 30. The gates 29 and 30 being held open for a fixed number of cycles by means of counter 32, and latching circuit 33. The logic units employed in this circuit are NAND gates. Specification 1116416 is referred to. |
